DESCRIPTION (Taken directly from the application) This is an application to establish a mouse phenotyping center to quantitatively evaluate liver gluconeogenesis, pyruvate recycling, the contribution of glycerol and Krebs cycle intermediates to glucose production, total glucose turnover, and citric acid cycle flux in live animals using a combination of 13C and 2H tracers and NMR spectroscopy. This standard metabolic assay provides the most comprehensive existing analysis of gluconeogenesis. It will be made available to on-campus and off-campus investigators having animal models of NIDDM or related disorders. In addition to the standard metabolic profile described above, a series of other phenotype specific metabolic techniques including a quantitative measure of substrate oxidation, measures of intracellular cations, and citric acid cycle flux using 13C enriched substrates will also be made available for selected animal models. A unique feature of this phenotyping center is that input will come from chemists, physicists, physiologists, computer scientists, physicians, and geneticists. All are recognized experts in 13C isotopomer analysis. A 400 MHz wide-bore NMR spectrometer will be dedicated to this project. All mice selected for phenotyping will be subjected to a standard protocol performed by high-level technicians; the data will be analyzed and interpreted by NMR spectroscopists and biochemists and made available through an interactive web site designed to allow the external investigators to test a fit of their isotopomer data to alternative metabolic models. A basic research core will focus on improving sensitivity through indirect detection of protons, develop an oral glucose tolerance test that includes 13C and 2H tracers, develop methods to measure fat oxidation in vivo, and extend measurements of extramyocellular adipose versus intramyocellular triglycerides in hind-limb mouse skeletal muscle. Finally, an administrative core will coordinate the activities of the three research cores and interface discussions between external investigators and center scientists.